Nanoprobes of all kinds have been investigated for penetrating single cells in various studies. These include semiconductor nanowires, tapered optical fibers, carbon nanotubes, and other variant structures. These devices have opened the door to single cell studies but have tended to lack any significant optical functionality on the part of the device probe itself. The former devices have mainly served the purpose of shuttling biological material in and out of cells and have also been used to simply illuminate or collect light inside the cell.
US 2013/0085398 is a representative example, where 3-D arrays of optical emitters or optical detectors are inserted into tissue. However, various practical problems need to be overcome in order to make such approaches practical.